The present invention relates to a glass-reinforced polymer composition and, more particularly, to a fiberglass-reinforced 4-methyl-1-pentene polymer composition.
It is conventionally known to mix glass fibers in a polyolefin to improve the mechanical properties of the polyolefin such as tensile strength, flexural strength, impact strength, or to improve the heat resistance. However, satisfactory improvements in the mechanical properties or heat resistance cannot be obtained if the polyolefin is simply mixed with the glass fibers, because the bonding strength between the polyolefin and glass fibers is weak.
In view of this problem, some measures have been proposed to improve the bonding strength between the polyolefin and the glass fibers.
For example, a method is proposed in Japanese Patent Publication No. 49-41096 wherein maleic acid or maleic anhydride, a polyolefin, and glass fibers which have been surface-treated with an aminosilane compound are reacted in the presence of an organic peroxide at a temperature higher than the melting point of the polyolefin. A method is also proposed in Japanese Patent Publication No. 52-31895 wherein a polyolefin, a modified poly-.alpha.-olefin having aromatic carboxylic acid units, and glass fibers which have been surface-treated with an aminosilane compound are melt-molded at a temperature higher than the melting point of the poly-.alpha.-olefin. Furthermore, U.S. Pat. No. 4,003,874 discloses a method for preparing a composition containing a modified polyolefin, a glass reinforcing material, and a nonmodified polyolefin, the modified polyolefin being obtained by kneading a mull of a polyolefin and maleic anhydride in the presence of an organic peroxide and in a nitrogen atmosphere.
Among polyolefins a 4-methyl-1-pentene polymer has a low density is light in weight, has a relatively high transparency, and is relatively inexpensive as compared to other polyolefins. However, due to its overall standards of mechanical properties, heat resistance and water resistance being poor, the 4-methyl-1-pentene polymer has not been fully utilised. Particularly, the 4-methyl-1-pentene polymer has not been able to be used in applications where a high standard of heat resistance is required, such as home electric appliances, automobile parts and the like.
Even if the conventional techniques for improving the properties of a polyolefin as described above are applied to a 4-methyl-1-pentene polymer, a satisfactory result cannot be obtained. As noted previously, the conventional techniques as described above include a treatment at a relatively high temperature, and a 4-methyl-1-pentene polymer tends to undergo thermal decomposition at such a high temperature, unlike other polyolefins such as polyethylene or polypropylene.